The distances to these interesting worlds can be hugely frustrating, and the brief time that spacecraft spend getting us data is never long enough. At Jupiter, Galileo gave us years and gigabytes of information. At Pluto… New Horizons had moments. But sometimes moments are enough to get just the right info to start something awesome.

New Horizons looked back at Pluto after its flyby and discovered the backlit planet haloed by illuminated haze. Sadly, that image set was New Horizon’s only chance to explore this phenomenon. Now, earthbound observers have taken to the sky with the SOFIA airborne observatory to study this haze with infrared and visible light detectors. While they can’t get stunning imagery, they can study Pluto in special moments when Pluto passes in front of a star, and its atmosphere gets backlit. This has added to New Horizons’ data and given us data over time. Predictions had been that Pluto’s atmosphere would collapse out as Pluto moved farther from the Sun, but the rate at which that is happening wasn’t matching pre-New Horizon models. With the new data and continued observations from SOFIA, they’ve proven that the particles in Pluto’s atmosphere are extremely small and able to stay lofted longer, allowing the haze to linger. This new work was led by Michael Person and appears in the journal Icarus.

More Information

• USRA press release
• NASA article
• “Haze in Pluto’s atmosphere: Results from SOFIA and ground-based observations of the 2015 June 29 Pluto occultation,” Michael J. Person et al., 2020, to appear in Icarus